The present invention relates to subterranean operations and, more particularly, to a method and system for opening and closing a subsurface valve used in conjunction with such operations.
Hydrocarbons, such as oil and gas, are commonly obtained from subterranean formations that may be located onshore or offshore. The development of subterranean operations and the processes involved in removing hydrocarbons from a subterranean formation are complex. Typically, subterranean operations involve a number of different steps such as, for example, drilling a wellbore at a desired well site, treating the wellbore to optimize production of hydrocarbons, and performing the necessary steps to produce and process the hydrocarbons from the subterranean formation.
When performing subterranean operations, it may be desirable to close off a well in the event of an uncontrolled condition that may damage property, injure personnel or cause pollution. One of the mechanisms used to close off a well is a Surface Controlled Subsurface Safety Valve (“SCSSV”). A SCSSV typically includes a flapper. The flapper is a closure member that may be pivotally mounted such that it is rotatable between a first “open” position and a second “closed” position. When in the closed position, the flapper may substantially close off the well. In certain implementations, a flow tube may be actuated downwardly against the flapper to rotate it into the open position. The flow tube may be actuated using a hydraulic control system. A closure spring may be mounted to the flapper's pivot rod. The closure spring may be biased so as to move the flapper back to its closed position once the actuation pressure applied to the flow tube is reduced below a pre-set amount.
The hydraulic control system used to actuate the flow tube may use a number of seals. A degradation of these seals may lead to a failure of the SCSSV, exposing the system to tubing pressure. It is therefore desirable to develop a hydraulic control system which retains the ability to close the flapper even if one or more of the SCSSV seals have been degraded.
While embodiments of this disclosure have been depicted and described and are defined by reference to examples set forth in the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.